CHAPTER III 

 CHEMISTRY OF COMMON THINGS 



8, Chemistry is the science which treats of the composi- 

 tion of substances. All substances are made up of very 

 small bodies or particles. If you place some water in a 

 vessel on a hot stove, the water will rapidly escape by 

 evaporation. How does it get out of the vessel? The 

 water on the road or sidewalk soon disappears after a 

 summer shower. Where does it go? How does it get 

 away? What other substances can be made to evapo- 

 rate? As you can divide a quart of water into drops, 

 so you can divide the drops into smaller bodies, and by 

 the use of heat the water can be divided into such tiny 

 particles that they can fly away in 'the air and not be 

 seen. 



You can take a piece of chalk or wood or coal and 

 divide it so that you would need a magnifying glass 

 or microscope to see the smallest parts. But the 

 smallest parts are still chalk, wood, or coal, like the 

 large piece from which they came. If you hold a cold 

 piece of iron over a vessel with boiling water in it, 

 the particles of water escaping will collect on the iron in 

 drops, and these drops will be water the same as that in 

 the vessel. This shows that the little particles escaping 

 from the water in invisible form are water. These little 

 particles of water, chalk, and coal which are too small to 

 be seen with the best microscopes are called molecules. 



